Beecher's Handouts /
Setting Exposure / 13.9 - Autoexposure Lock
Most digital SLR (DSLR) cameras have an autoexposure lock button.
On Nikons, the button is labeled with AEL, and on Canons, with
a star.
The button is usually located on the back of the camera, to the
right, where it can be pressed by your thumb.
When you press and hold the AEL button, the exposure is locked.
AFL, Too?
The AEL button often does double duty as an autofocus lock button.
In your camera menu, you can set the button to:
• Lock in both the exposure and the focus.
• Lock in only the exposure.
• Lock in only the focus.
You may want to set the button to lock in only the exposure.
Example #1
If you're at the Grand Canyon, point your camera down at the
canyon.
Press and hold the AEL button.
The exposure is now set for the canyon, and not the bright sky.
With the AEL button still depressed, point your camera at the
sky and canyon, and press the shutter release.
Example #2
Let's say you're photographing a friend standing on the edge
of the canyon, with a bright sky behind them.
If you don't use the AEL button, the camera may set the exposure
for the bright sky.
Your friend will be in silhouette against the sky.
Instead, walk up to your friend, fill the frame with his or her
face.
Press and hold the AEL button.
The exposure is now set for your friend, not the sky.
While keeping the AEL depressed, walk back and focus, and press
the shutter release.
Spot Metering
You can set your light meter to see only a tiny area in the middle
of the frame.
This is called spot metering.
In example #2 above, you could measure the light on your friend's
face, without having to walk up close.
Just set your light meter to spot metering, center your friend's
face in the middle of the frame, and press and hold the AEL button.
The exposure is now set for their face, and you didn't have to
walk up close to their face.
Look in the instruction manual for light metering options, and
learn how to switch to spot metering.
